Question of the Week

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The SS American Mariner


In the 1950s, the US Maritime Administration commissioned several classes of single-screw break bulk cargo vessels. The SS American Mariner, technically a C4-S-1a vessel, is used in US Coast Guard examinations as the platform for various stability calculations. Originally these questions only appeared on Unlimited Master AGT and Unlimited Chief Mate AGT exams. Now they can be found on exams for Masters 500/1600 NC/Oceans, and Mates 500/1600/AGT NC and [...]

The SS American Mariner2020-08-15T19:35:23-07:00

Loading & Unloading Oil Cargoes: Calculations


Many of the Deck Examinations on the new "Q" tests contain two types of questions about loading and unloading oil cargoes. Both require calculation. The first asks for a quantity. The second wants to know the time and date of final loading. To determine the quantity of oil cargo loaded or discharged, remember two things. First, oil cargoes expand or contract depending upon temperature and second, "net" barrels are [...]

Loading & Unloading Oil Cargoes: Calculations2020-03-31T11:37:36-07:00

Elbow Room: Staying Within an Anchorage


You are arriving in port and are assigned to anchor in anchorage circle B-4. It has a diameter of 500 yards and your vessel's LOA is 484 feet. If you anchor in 8 fathoms at the center of the circle, what is the maximum number of shots of chain you can use and still remain in the circle? There are two ways to solve these kinds of problems.  One [...]

Elbow Room: Staying Within an Anchorage2020-08-15T16:51:08-07:00

Minimum Freeboard


At small angles of inclination, a vessel’s stability is indicated by her GM or metacentric height. But when a vessel encounters conditions that cause her to roll, heave, pitch, sway and yaw excessively, for example in heavy or rough seas, she needs reserve buoyancy to counter the effects of these forces. Reserve buoyancy is the volume of enclosed spaces above the waterline and is measured by freeboard. Generally, more [...]

Minimum Freeboard2019-06-16T14:05:40-07:00



It is hard to imagine the pleasure of drinking wine being diminished by not knowing the name of the indentation in the bottom of the wine bottle.  And plenty of shoes have been successfully tied by people who do not know the name of the thingamajig at the end of a shoelace.  It’s the same with ground tackle onboard ship.  Anchors have been heaved, weighed, dragged, dredged, kedged, dropped underfoot [...]


ETA (Estimated Time of Arrival)


Near Coastal and Celestial examinations for deck licenses will often include an ETA (Estimated Time of Arrival) problem. The more interesting of this type are trans-Pacific crossing the International Date Line. The trick to these problems is not to think — not to think about the Date Line or the date or the direction of travel.  Instead, translate all times (departure, elapsed and arrival) through Greenwich.For example: Here is a [...]

ETA (Estimated Time of Arrival)2018-10-13T23:51:17-07:00

Get Smart, Go Astern


In a study published in Psychological Science (May 2009), Dutch researchers determined that “Backward locomotion appears to be a very powerful trigger to mobilize cognitive resources.” The Rules of the Road anticipated this conclusion in Rule 8 by advising that “if a vessel needs more time to avoid collision or assess the situation, she shall slacken her speed or take all way off by stopping or reversing her means [...]

Get Smart, Go Astern2018-10-13T23:45:42-07:00

Chart Projections


In 1849, Dr. Samuel Birley Rowbotham published the pamphlet “Zetetic Astronomy: Earth Not a Globe”  in which he asserted that the Earth is an enclosed plane, surrounded by the ice of Antarctica and (somehow) suspended over which are the stars, the Sun, the Moon and the planets. Nearly three hundred years later, the astrophysicist Neil DeGrasse Tyson found himself in a smackdown with Rowbotham soul-mate and rapper B.o.B., arguing that [...]

Chart Projections2018-10-04T20:02:10-07:00

“Full and Down” Calculations


“Full and Down” describes the desirable but rare condition in which a vessel has all her cargo space filled and is loaded down to her Plimsoll marks.  Achieving the state of “full and down”  requires some arithmetic.  The old examination bank of questions has three “full and down” problems, two of which require elementary algebra.  The new examination bank has dropped two of these questions leaving only one relatively simple calculation problem. Before [...]

“Full and Down” Calculations2018-10-04T20:16:22-07:00

Calculating Board Feet


Occasionally it is necessary to calculate the number of board feet in a pile of lumber.  The key to the problem is knowing that a board foot is 1′ (long) x 1′ (wide) x 1″ (high).  In other words in every cubic foot of lumber (1′ x 1′ x 1′), there are 12 board feet; the cubic foot makes twelve 1-inch slices of wood. You are to load a consignment [...]

Calculating Board Feet2018-09-30T12:11:56-07:00

Marine Insurance & the Restraint of Rulers, Princes or People


Masters and Chief Mates are occasionally asked the following question: What is an example of the term "Restraint of Rulers, Princes, or Peoples" in a marine insurance policy? A. A prohibition from loading a cargo from a country's government interference B. Arrest of a vessel by legal authorities to satisfy claims through exercise of a maritime lien C. Damage caused by riot of the population of a port D. [...]

Marine Insurance & the Restraint of Rulers, Princes or People2020-09-13T14:50:06-07:00

Submarine Emergency Identification Signals


The US Navy has long authorized certain submarine emergency identification signals.  In the past, these signals could be found in Chapter 1 of a current Coast Pilot.  No more.  Notice to Mariners No. 1, the first publication each year of the weekly NTMs, includes a section called “Special Notice to Mariners Paragraphs” describing, among many other marine safety topics, the Submarine Emergency Identification Signals (I-1.7). USCG examinations will continue to include [...]

Submarine Emergency Identification Signals2020-01-25T21:17:54-08:00

The Great Lakes


In the past, with the exception of examinations specific to Great Lakes’ licenses, USCG “Rules of the Road” questions have not asked for the extended definition of these waters as described in Rule 3(m) Inland. They do now. The mnemonic “HOMES—H(uron), O(ntario), M(ichigan), E(rie), S(uperior)” no longer suffices to answer the questions “What is . . . “ and “What is not . . . “ considered part of the [...]

The Great Lakes2018-10-05T09:48:35-07:00

Reeving a Block


Archimedes boasted “Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.” An application of the same mighty principle of leverage is found in the blocks and tackles that are used to lift weights on board ship and in the construction industry. “Give me a rope long enough, and I shall lift the world.” “Mechanical Advantage” is defined [...]

Reeving a Block2018-10-05T10:34:55-07:00

Magnificent Beast: The Northern Right Whale


In order to protect the dwindling number of Northern Right Whales, the “Marine Mammal Protection Act” of 1972 mandated that the amazing “Eubalaena Glacialis” be given wide berth by, among others, mariners.  As reported in The New York Times in March 2009, the MMPA was working; the population of Northern Right Whales had increased. But the  death of a young female off Cape Cod, possibly from a collision with a ship, [...]

Magnificent Beast: The Northern Right Whale2019-07-13T12:34:18-07:00

Chronometer Error and Chronometer Rate


Greenwich Mean Time is invaluable to the navigator and the chronometer is the instrument which provides it. But like any instrument, the chronometer is subject to error. Routinely, candidates for Ocean and Near Coastal deck credentials are required to determine Chronometer Error and Chronometer Rate. This week we will do both. Chronometer Error (Stopwatch) You are taking a time tick using the 1400 signal from Kekaha-Kauai, Hawaii (WWVH). You [...]

Chronometer Error and Chronometer Rate2020-01-25T21:20:37-08:00

Determining Shackle Size


Shackles are a primary means of connecting the parts of rigging systems on vessels and industrial cranes.  In its simplest form, a shackle is a U-shaped piece of metal secured by a clevis pin, screw or bolt at its opening.  Shackles range in size from this extraordinarily large forged wide-body shackle capable of managing a working load of 2500 metric tons to these amethyst and gold shackle earrings, whose lifting [...]

Determining Shackle Size2018-10-05T09:35:42-07:00

The Tropical Wave


Tropical Cyclones just don’t blow in unannounced.  What eventually becomes a named meteorological event begins as a tropical wave (Bowditch calls it an “easterly wave,” elsewhere it is known as an “African easterly wave”) and progresses from this stage to become a tropical disturbance. If conditions are encouraging, it evolves into a tropical depression and the isobars close. If really disturbed it morphs into a tropical storm.  And if not [...]

The Tropical Wave2018-10-13T12:39:55-07:00
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